Longitudinal Changes in Airway Remodeling and Air Trapping in Severe Asthma

Rationale and Objectives: Previous cross-sectional-studies have demonstrated that airway wall thickness and air trapping are greater in subjects with severe asthma than in those with mild-to-moderate asthma. However, a better understanding of how airway remodeling and lung density change over time is needed. This study aimed to evaluate predictors elf airway wall remodeling and change in lung-function and lung density over time in Severe asthma. Materials and methods: Phenotypic characterization and quantitative multidetector-row computed tomography (MDCT) of the chest were performed at baseline and similar to 2.6 years later in 38 participants with asthma (severe n = 24 and mild-to-moderate n = 14) and nine normal I controls from the Severe Asthma Research Program. Results: Subjects with severe asthma had a significant decline in postbronchodilator forced expiratory volume in 1 second percent (FEV1%) predicted over time (P < .001). Airway wall thickness measured by MDCT was increased at Multiple airway generations in severe asthma compared to mild-to-moderate asthma (wall area-percent [WA%]: P < .05) and normals P < .05) at baseline and year 2. Overtime, there was an increase in WA% and wall thickness percent (WT%) in all subjects (P = .030 and .009, respectively) with no change in emphysema-like lung or air trapping. Baseline prebronchodilator FEV1% inversely correlated with WA% and WT% (both P < .05). In a multi-variable regression model, baseline WA%, race, and health care utilization were predictors of Subsequent airway remodeling. Conclusions: Severe asthma Subjects have a greater decline in lung function over time than normal subjects or those With mild-to-moderate asthma. MDCT provides a noninvasive measure of airway wall thickness that may predict subsequent airway remodeling.